Ram air flap system

ABSTRACT

An assembly for increasing air flow to a vehicle cooling system includes a portion of a cooling fan shroud, the portion having a face defining an opening therethrough, and a plurality of support members extending from the face. A flap includes a plurality of apertures proximal to an edge. Each aperture of the plurality of apertures is formed to receive one of the plurality of support members for coupling the flap thereto. A clearance fit formed between the apertures and the support members permits movement of the flap from a first position generally parallel to the face to a second position in response to a flow of air.

BACKGROUND

The present invention relates to ram air flap systems for vehicles, andspecifically to a ram air flap system for increasing air flow toportions of a vehicle cooling system at increased vehicle speeds.

SUMMARY

In one embodiment of an assembly for increasing air flow to a vehiclecooling system, the assembly includes a portion of a cooling fan shroud,the portion having a face defining an opening therethrough, and aplurality of support members extending from the face. A flap includes aplurality of apertures proximal to an edge. Each aperture of theplurality of apertures is formed to receive one of the plurality ofsupport members for coupling the flap thereto. A clearance fit formedbetween the apertures and the support members permits movement of theflap from a first position generally parallel to the face to a secondposition in response to a flow of air.

In one embodiment of a cooling fan shroud for a vehicle, the cooling fanshroud includes a cooling fan shroud face having a primary openingtherethrough for a cooling fan, a plurality of secondary openingstherethrough, and a plurality of support members extending from the faceadjacent each secondary opening. A flap includes a plurality ofapertures proximal to an edge, each aperture of the plurality ofapertures formed to receive one of the plurality of support members forcoupling the flap thereto. A clearance fit formed between the aperturesand the support members permits movement of the flap from a firstposition generally parallel to the shroud face to a second position inresponse to a flow of air.

In one embodiment of a method of producing a cooling fan shroud, themethod includes injection molding a shroud portion having a facedefining an opening therethrough, a plurality of support membersextending from the face, and a guide member adjacent the opening andextending from the face. The method further includes coupling a flap tothe plurality of support members. The coupling includes flexing the flapto engage the support members of the plurality of support members.

In one embodiment of an assembly for increasing air flow to a vehiclecooling system, the assembly includes a portion of a cooling fan shroud.The portion has a face defining an opening therethrough and a pluralityof support members extending from the face. A flap includes a pluralityof apertures proximal to an edge, each aperture of the plurality ofapertures formed to receive one of the plurality of support members forcoupling the flap thereto. A clearance fit formed between the aperturesand the support members permits movement of the flap from a firstposition generally parallel to the face to a second position in responseto a flow of air. The flap is retained on the shroud portion at leastpartially by one or more elastic members attached to the shroud portionor formed as an integral part of the shroud portion. The elastic membersare flexed during engagement of the apertures with the support members.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a radiator cooling fan shroud incorporating aram air flap system.

FIG. 2 is a partial perspective view of a portion of the fan shroud ofFIG. 1.

FIG. 3 is a perspective view of a ram air flap for use with the shroudportion of FIG. 2.

FIG. 4 is a partial perspective view of the shroud portion of FIG. 2with the flap of FIG. 3.

FIGS. 5 a-5 c are cross sectional views illustrating assembly of theflap of FIG. 3 onto the shroud portion of FIG. 2.

FIG. 5 d is a cross sectional view of the flap of FIG. 4 closed.

FIG. 5 e is a cross sectional view of the flap of FIG. 4 open.

FIG. 6 is a partial perspective view of a portion of another fan shroud.

FIG. 7 is a partial perspective view of a portion of another fan shroud.

FIG. 8 is a partial perspective view of a portion of another fan shroud.

FIG. 9 is a partial perspective view of a portion of another fan shroud.

FIG. 10 is an exploded view of a portion of another fan shroud and aflap.

FIG. 11 is a perspective view of the flap of FIG. 10 during assembly.

FIG. 12 is a perspective view of the assembled shroud portion and flapof FIG. 10.

FIG. 13 is an exploded view of a portion of another fan shroud and aflap.

FIG. 14 is a perspective view of the assembled shroud portion and flapof FIG. 13.

FIGS. 15 a-15 d are cross sectional views illustrating assembly ofanother flap onto a portion of another fan shroud.

FIG. 16 is a partial perspective view of a portion of another fanshroud.

FIG. 17 is a perspective view of the shroud portion of FIG. 16 assembledwith a flap.

FIG. 18 is a perspective view of the shroud portion of FIG. 16 assembledwith another flap.

FIG. 19 is a perspective view of the shroud portion of FIG. 16 assembledwith the flaps of FIGS. 17 and 18.

FIG. 20 is a partial perspective view of a portion of another fanshroud.

FIG. 21 is a perspective view of the shroud portion of FIG. 20 assembledwith a flap.

FIG. 22 is a side view of the shroud portion and flap of FIG. 21.

FIG. 23 is a partial perspective view of a portion of another fan shroudassembled with a flap.

FIG. 24 is a side view of the shroud portion and flap of FIG. 23.

FIG. 25 is a front view of the shroud portion of FIG. 23 without a flap.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. And as used herein and in the appendedclaims, the terms “upper”, “lower”, “top”, “bottom”, “front”, “back”,and other directional terms are not intended to require any particularorientation, but are instead used for purposes of description only.

FIG. 1 illustrates a vehicle radiator cooling fan 10 contained within acooling fan shroud 20. The shroud 20 presents a rear surface 30 directedtoward the engine block of the vehicle, and the fan 10 is generallycentrally located within the shroud. The fan 10, assisted by the shroudgeometry, operates to draw and direct air across the radiator coils (notshown) to transfer internal engine heat from the cooling medium to thepassing air in a manner known to those of skill in the art. In someembodiments, the cooling fan shroud 20 is positioned behind the radiatorto guide air to the fan 10, and in other embodiments the cooling fanshroud 20 is positioned in front of the radiator, in which case theshroud 20 directs air passing through the fan 10 over the radiatorcoils. A plurality of ram air flap assemblies 100 are integrated withthe rear surface 30 to form a ram air flap system to provide increasedair flow across the radiator coils, as described herein.

The fan shroud 20 is preferably an injection-molded uniform component,of which separate portions include features of each individual flapassembly 100. The portions represent sections of the fan shroud 20 andare preferably integrally formed concurrently with the molding of theshroud 20, but in some applications may be separate injection-moldedsections added to a fan shroud (with necessary modifications). FIGS. 2-3illustrate a particular portion 110 of the fan shroud 20 and a flap 120.The portion 110 includes a rear face 128 defining one or more openings132. The portion 110 is approximately 120 mm to 140 mm wide (length “W”)and approximately 40 mm to 50 mm high (length “H”), though the size maybe dependent on the particular application. Referring to FIG. 2, theopenings 132 may be considered as two distinct openings or one openingseparated by a support member or rib 136. The support rib 136 can becontinuous or non-continuous and exhibit a variety of linear ornonlinear shapes.

The portion 110 further includes a plurality of support members 144extending from the rear face 128. The support members 144 are generallyhook-shaped and define a contoured supporting surface 148 for securingthe flap 120, further described below. The support members 144 can beevenly spaced laterally across the rear face 128, or may be offsettoward one of the portion edges 142, or may alternatively be mirroredabout an approximate centerline bisecting the width W of the portion110.

In some embodiments, the support members 144 adjoin a lateral arcuaterecess 152 that permits operational deflection of the flap 120 to anopen position, as will be further described. The recess 152 ispreferably molded with the fan shroud 20 but can optionally be machinedor otherwise formed subsequent to the molding process. As shown mostclearly in FIG. 2, a portion of the recess 152 may be removed in thevicinity of each support member 144. A guide member or rib 160projecting from the rear face 128 extends along a substantial portion ofthe portion 110 adjacent to the recess 152. The guide rib 160 presentsan underside surface 164 cooperative with the recess 152 to seat theflap 120, as will be further described below. Though preferably moldedwith the fan shroud 20, the support members 144 and guiding rib 160 maybe separate components secured to the fan shroud 20, such as through asubsequent molding step.

As shown in FIG. 3, the flap 120 is a generally planar member with arear face 170 and is preferably punched from a relatively thick-walled,extruded or rolled film, for example, a thermoplastic. Suitablethermoplastics may include, but are not limited to, stabilizedpolypropylene, polyamide, or polybutylene terephthalate, as well ashigh-temperature polyethylenimine and polyphenylene sulfide, any ofwhich can be extruded into films and subsequently punched or cut, andwhich may include radiating cross-linking. In some applications,elastomers, silicons, or other extrudable plastics may be suitable, andthe flap material may additionally be integrated with fibrous fillers ora fabric during the extrusion process. A composite of any of theaforementioned films may also be used in certain applications. A metalfoil, preferably of a corrosion-proof alloy or painted or otherwisecoated for corrosion protection may also be used. The flap thickness canrange from about 0.05 to about 0.8 mm.

The flap 120 is sized to cover the opening(s) 132 when in a closedposition, which can be considered substantially parallel to the rearface 128. A plurality of apertures 174, the edges of which are generallyrounded to reduce stress concentration, are similarly punched or cutfrom the flap 120 near a top edge 178 and spaced to receive theplurality of support members 144.

Because the width of the assembly 100 can vary from application toapplication, a continuous film can be punched or cut to length to form aflap corresponding to a particular width and having a predeterminedaperture separation. In such a situation, not all apertures 174 need tocorrelate with a support member 144. The flap itself may include areasof differing thickness for reinforcement purposes, for example, anadditional supporting rib or ribs 180 formed during the extrusionprocess.

Referring to FIG. 4, the flap 120 is shown mounted to the supportmembers 144. Each support member 144 extends through a correspondingaperture 174, retaining the flap 120.

Referring to FIGS. 5 a-5 e, in assembly the top edge 178 of the flap 120is guided along the underside surface 164 of the guide rib 160. As thetop edge 178 contacts the junction of portion 110 or recess 152 with theunderside surface 164, continued insertion flexes, or elasticallydeforms, the relatively rigid flap 120 as it proceeds further into therecess 152 (FIG. 5 b) or along portion 110. Once the top edge 178 passesacross the end of the respective support members 144, the supportmembers pass through the apertures 174, seating the flap 120 (FIGS. 5c-5 d). The guide rib underside surface 164 is positioned to limit thetravel of the flap 120 and thereby hinder removal of the flap 120without affirmatively flexing the flap 120 to pass the aperture(s) 174back over the ends of the respective support members 144 (see, e.g.,FIGS. 5 c and 5 b).

In operation, as the vehicle speed increases, the velocity of the airrelative to the vehicle increases. The position of the assembly 100within the cooling fan shroud 20 exposes the openings 132 frontally tothis air. The interaction of air with the flap 120 (due to dynamicpressure effects) deflects the flap 120 from a first position rearwardto a second position, shown in FIG. 5 e, and allows the ram air to passthrough the opening(s) 132 to or from the radiator coils (not shown).The flap 120 is allowed to move to the second position at least in partby a clearance fit, which allows the apertures to move relative to thesupport members. Therefore, the apertures in the flaps show a biggerarea than the cross section of the support members. The amount ofmovement of the flap 120 is related to the velocity of the air, with theguide rib 160 providing an operational travel stop for the flap 120during maximum deflection, as best seen in FIG. 5 c. A typical openingangle is about 70°, which permits good airflow and additionally lowerspacking depth. Further, self-closing by gravity and suction flow ispromoted by such an arrangement. As the vehicle velocity decreases,diminishing dynamic pressure from the air permits the flap 120 to moveback, by gravity, to the first position (FIG. 5 d). In the firstposition, the flap 120 additionally prevents short circuiting of air,i.e., in the absence of a flap 120, operation of the cooling fan 10 whenthe vehicle is not moving would permit portions of air passing throughthe cooling fan 10 to flow back in a reverse direction through theopening(s) 132, as indicated by the arrows of FIG. 5 d. Such a situationlessens the amount of heat transferred from the radiator.

Referring to FIGS. 6-9, the features of each portion 110 of the fanshroud 20 can be varied to accommodate different applications. Forexample, FIG. 6 illustrates openings 132 further defined by a skirtportion 182 extending from the rear face 128 and presenting a contactsurface 184 for contact with a front surface of the flap 120. As such,the flap 120 need not lie flush with the rear face 128 when in the firstor closed position but rather rests against or is generally parallel tothe skirt portion 182. FIG. 7 shows a single opening 132 having a skirtportion 182 and a support tab 190 to provide additional contact area forthe flap 120 without substantially blocking the opening 132 for ram airflow. As shown, three support members 144 may be formed in the portion110, with a center support member 144 generally aligned with the supporttab 190. Referring to FIGS. 8 and 9, three or more openings 132 can beutilized with a significantly wider portion 110.

Referring to FIGS. 10-12, another flap assembly 200 includes a shroudportion 210 with a rear face 214 defining an opening 218. An optionalsupport rib (not shown) can be molded therein for additional support.Thus, the portion 210 may have a plurality of openings 218.

As shown in FIG. 10, the portion 210 includes two mirrored supportmembers 224 extending from the rear face 214 and presenting an undercutsurface 228. A generally planar flap 240 with a rear face 244 and firstand second edges 248 is punched or cut from a suitable extruded orrolled thermoplastic, as previously described. The flap 240 includesapertures 250 sized and spaced near a top edge 254 to correspond withthe support members 224.

As illustrated, when the flap 240 is in a non-flexed condition, theapertures 250 are spaced wider than what would permit a simple passingof the apertures 250 over the support members 224. To secure the flap240 to the shroud body 210, a user must force the first and second edges248 toward each other, flexing the flap 240, as shown in FIG. 11.Flexing the flap 240 brings the apertures 250 to a position in whichthey can be passed over the support members 224. Once so positioned,upon release of the first and second edges 248, the flap 240 retains itsnatural unflexed state such that the undercut surfaces 228 hinderseparation of the flap 240 during operational conditions, as shown inFIG. 12.

FIGS. 13 and 14 illustrate an alternative embodiment with a flapassembly 260 including a shroud portion 262 with a rear face 268defining an opening 272, which may or may not include a support rib, aspreviously described.

The shroud portion 262 includes two support members 276 extending fromthe front face and generally shaped as ‘mushrooms’ or buttons with anundercut surface 280. A flap 284 is a generally planar member with twoapertures 288 geometrically configured for elastic expansion. Forexample, the primary oval shape of each aperture 288 in the flap 284 asshown in FIG. 13 is bisected by a laterally extending notch 292 thatpermits the expansion of the entirety of each aperture 288 when appliedover the support members 276. The undercut surface 280 of each supportmember 276 retains the flap 284 during operation.

Additional support structure and flap aperture configurations permitsimplified assembly while preventing separation of the flap from the fanshroud during operation. For example, FIGS. 15 a-15 e show a portion 310of the fan shroud 20 with two support members 314 similar to the supportmembers 224 of FIGS. 10-12 and a flap 320 with generally rectangularapertures 324 offset to one side of the flap 320 and sized to pass overthe support members 314. The portion 310 also includes an elasticelement 330 configured to partially deflect into a formed recess 334 andpresent an abutment surface 340.

During assembly, passing the flap apertures 324 over the respectivesupport members 314 concurrently deflects the elastic element 330frontward toward the recess 334. The deflection permits the flap 320 topass fully over the support members 314. Once in position, the flap 320is moved laterally (leftward in FIG. 15 b), which allows the elasticelement 330 to spring back into its natural position (FIG. 15 c),disposing the abutment surface 340 adjacent an end 344 of the flap 320to hinder movement of the flap 320 that might inadvertently align theapertures 324 with the support members 314, facilitating possibleremoval of the flap 320 during operation. In one alternative illustratedin FIG. 15 d, the shroud body material forming the recess is replacedwith an aperture 348 permitting the same amount of deflection of theelastic element during assembly.

The shroud and flap features of the aforementioned embodiments are in noway limiting and, for example, the support members may include one orthree or more support members, which could embody differing shapeshaving the characteristic of retaining the flap to the shroud duringoperation. The shroud and flap may include additional surface finishesand treatments (e.g., stretching, coating, printing, or tempering) orother work subsequent to molding, e.g., rounding or bending of cornersand edges, or the addition of further cutouts, notches, grooves, orindentations in an effort to improve aerodynamics and acoustics, and tominimize air leaks. In some applications, a sealing lip can be formed ona bottom edge of the flap for such a purpose. In other applications, theouter contour of the flap may contain recesses or other features tofacilitate packaging and overcome space restraints.

Referring to FIGS. 16-19, a shroud portion 110 of the fan shroud 20 issimilar to that shown in FIGS. 6 and 7, and like features are referencedwith like numbers. The support members 144 of FIGS. 16 and 17accommodates the flap 120 previously described. A catch member 400integrally molded with or subsequently fixed to fan shroud portion 110at a first end 404 includes a second end 408 configured to block furthermovement of the flap 120 to a fully open position, as shown in FIG. 17.Specifically, the catch member 400 acts to limit the amount ofdeflection of the flap 120 to, for example, approximately 60° from thefirst position. Limited deflection decreases the amount of spacenecessary for operation and promotes more rapid self-closing of the flapassembly. The portion 110 of FIGS. 16-18 further includes first andsecond opposing pivot members 420 extending laterally into at least aportion of the opening 132 and defining a pivot axis 424. A separateflap 430 of a molded construction sized to cover the opening 132 ispivotally coupled to the pivot members 420 and thereby rotatable aboutthe pivot axis 424 as illustrated in FIG. 18. Specifically, the flap 430is configured such that it is mounted offset to the pivot axis 424, forexample, at an approximate 1/3 to 2/3 ratio, i.e., for a uniformconstruction, approximately 2/3 of the surface area is on one side ofthe pivot axis 424. The ram air affects the greater surface area to agreater degree and thereby rotates the flap 430 about the pivot axis424. As with the flap 120, decreasing the velocity of the vehiclelessens the rotative effect on the flap 430 and the flap 430 returns bygravity to its natural closed position covering the opening 132.Referring to FIG. 19, the flap 120 and the flap 430 can, in someapplications, be included together to cover the same opening 132.

Referring to FIGS. 20-22, another flap assembly 500 includes a shroudportion 510 having a rear face 514 with a skirt 520 defining openings524. A plurality of support members 530 similar to support members 144of FIGS. 2-4 extend laterally across the shroud body 510 to support aflap 534 in a manner previously described. A pronounced guide rib 540across the top of the shroud body 510 includes an underside surface 544that cooperates with recessed area 548 of the shroud body 510 to seatthe flap 534, as previously described with respect to FIGS. 5 a-5 c.

FIGS. 23-25 illustrate another embodiment of a flap assembly 600 inwhich a shroud portion 610 with a skirt 620 defines openings 624, andfurther includes support members 630, all of which are constructed andfunction similarly to previously described embodiments. As with theother embodiments herein, the support members 630 can be formed asmirrored about or offset from the approximate center of the portion 610separating the openings 624. An integrally formed cantilevereddeflection-limiting portion 640 extends rearward and includes aplurality of downwardly-protruding stops 644. A flap 650 is retained bythe support members as previously described.

In operation, the deflection of the flap 650 due to interaction with theoncoming ram air deflects the flap 650 upward from a first position to asecond position, as shown most readily in FIG. 24. The second positionis limited by the position of the downwardly protruding stops 644irrespective of the relative air velocity. For example, the stops 644may limit the deflection of the flap 650 to approximately 60° from thefirst position.

The ram air flap assemblies and systems herein described are relativelyeasy to manufacture and, because the flaps are punched or cut from athick-walled, extruded or rolled film, reduce material and manufacturingcosts. Because deformation is not necessary during operational openingand closing of the flap(s), the greater wall thickness provides a morerobust design with which to withstand engine compartment operating ormaintenance conditions, including moisture, heat, vehicle fuel, steamjet cleaning, gravel or particulate impact, and splash water. Inaddition, the straightforward linear movement of the flap onto thesupport members effects comparatively quicker and easier assembly.

Various features and advantages of the invention are set forth in thefollowing claims.

1. An assembly for increasing air flow to a vehicle cooling system, the assembly comprising: a portion of a cooling fan shroud, the portion having a face defining an opening therethrough, and a plurality of support members extending from the face; and a flap including a plurality of apertures proximal to an edge, each aperture of the plurality of apertures formed to receive one of the plurality of support members for coupling the flap thereto, wherein a clearance fit formed between the apertures and the support members permits movement of the flap from a first position generally parallel to the face to a second position in response to a flow of air.
 2. The assembly of claim 1, wherein the cooling fan shroud includes a recess integrally formed in the face adjacent the plurality of support members, wherein the recess accommodates movement of the edge as the flap moves from the first position to the second position.
 3. The apparatus of claim 1, wherein the shroud portion further includes at least one guide member adjacent to the recess and extending from the face, the guide member cooperative with at least one support of the plurality of supports to limit movement of the flap to the second position.
 4. The apparatus of claim 3, wherein the second position is approximately 60° from the first position.
 5. The apparatus of claim 1, wherein the flap blocks the opening in the first position.
 6. The apparatus of claim 1, wherein the flap is punched from one of an extruded and a rolled film.
 7. The apparatus of claim 1, wherein the flap is cut from one of an extruded and a rolled film.
 8. The apparatus of claim 1, wherein the flap is constructed of a thermoplastic, elastomer, or metal.
 9. The apparatus of claim 1, wherein the opening is a first opening and wherein the face further defines a second opening therethrough, the second opening separated from the first opening by a support member.
 10. The apparatus of claim 1, wherein the flap further includes a reinforcement member generally orthogonal to the edge.
 11. The apparatus of claim 1, wherein the recess is arcuate in cross-section.
 12. The apparatus of claim 1, wherein the shroud portion further includes opposing pivot supports projecting across a portion of the opening and defining a pivot axis operable to support a rotatable flap.
 13. The method of claim 1, wherein the thickness of the flap is between 0.05 to 0.8 mm.
 14. A cooling fan shroud for a vehicle, the cooling fan shroud comprising: a cooling fan shroud face having a primary opening therethrough for a cooling fan, a plurality of secondary openings therethrough, and a plurality of support members extending from the face adjacent each secondary opening; and a flap including a plurality of apertures proximal to an edge, each aperture of the plurality of apertures formed to receive one of the plurality of support members for coupling the flap thereto, wherein a clearance fit formed between the apertures and the support members permits movement of the flap from a first position generally parallel to the shroud face to a second position in response to a flow of air.
 15. A method of producing a cooling fan shroud, the method comprising: injection molding a shroud portion having a face defining an opening therethrough, a plurality of support members extending from the face, and a guide member adjacent the opening and extending from the face; and coupling a flap to the plurality of support members, wherein the coupling includes flexing the flap to engage the support members of the plurality of support members.
 16. The method of claim 15, wherein coupling a flap to the plurality of support members means coupling a flap having a plurality of apertures along a first edge, the apertures spaced to each receive one of the plurality of support members.
 17. The method of claim 15 wherein coupling a flap to the plurality of support members means coupling a flap having a thickness of between 0.05 to 0.8 mm.
 18. The method of claim 16, wherein coupling the flap to the plurality of support members includes elastically deforming the flap to position each of the plurality of apertures over each of the plurality of support members.
 19. The method of claim 16, wherein coupling the flap to the plurality of support members includes elastically deforming the flap between the guide member and the plurality of support members such that an end of each support member of the plurality of support members extends through a respective aperture of the flap.
 20. The method of claim 18, further including guiding the flap along the guide member into a recess.
 21. The method of claim 15, wherein injection molding the shroud portion means injection molding the guide member to be disposed cooperatively with at least one support of the plurality of supports to limit operable movement of the flap.
 22. An assembly for increasing air flow to a vehicle cooling system, the assembly comprising: a portion of a cooling fan shroud, the portion having a face defining an opening therethrough, and a plurality of support members extending from the face; and a flap including a plurality of apertures proximal to an edge, each aperture of the plurality of apertures formed to receive one of the plurality of support members for coupling the flap thereto, wherein a clearance fit formed between the apertures and the support members permits movement of the flap from a first position generally parallel to the face to a second position in response to a flow of air, and wherein the flap is retained on the shroud portion at least partially by one or more elastic members attached to the shroud portion or formed as an integral part of the shroud portion, the elastic members being flexed during engagement of the apertures with the support members. 